Different parts of the United States have experienced outbreaks caused by bacteria and viruses in recent months. Some of these events have approached epidemic levels, while others have been relatively small in scale. Five such outbreaks are detailed below.

Meningococcal disease

Officials with Oregon State University in Corvallis confirmed five cases of meningococcal disease among students this year. The fifth case occurred in an undergraduate who was hospitalized Nov. 24 and reported to be in good condition as of Nov. 27. The four other students infected earlier this year were treated for the infection and have recovered.

Meningococcal disease is caused by the bacteria Neisseria meningitidis. Infection with the bacteria first presents as a flu-like illness, before rapidly worsening. The illness can cause infections of the brain or spinal cord (meningitis) and infections of the blood (septicemia).

The Kentucky Department for Public Health officially declared a statewide outbreak of hepatitis A Nov. 21. While Kentucky has reported an average of 20 hepatitis A cases annually over the last decade, the state has seen 31 confirmed cases in multiple counties throughout the state this year, marking a 50 percent increase.

Symptoms of hepatitis A infection include abdominal pain, low-grade fever, nausea, fatigue and jaundice. The virus is highly transmissible and most often spread via contact with fecal matter from an infected individual.

The hepatitis A genotype identified in the Kentucky outbreak is the same genotype responsible for California's . The California outbreak caused 644 cases, 420 hospitalizations and 21 deaths as of Nov. 3.

Legionnaires' disease

Disneyland Park in Anaheim, Calif., shut down two of its 18 cooling towers Nov. 1 after local health officials informed theme park administrators of nine cases of Legionnaires' disease among individuals who visited the park in September.

Orange County Health Care Agency identified three additional cases of Legionnaires' among individuals who had been to Anaheim, but not Disneyland. In total, 10 of the infected individuals were hospitalized. One patient with additional health issues died. Infected individuals were between the ages of 52 and 94.

Legionnaires' disease is a virulent type of pneumonia caused by Legionella bacteria. The illness can be contracted by inhaling mist from infected water sources, such as cooling towers, steam rooms and plumbing systems. It is not spread by person-to-person contact or by drinking water.

Mumps

Health officials with Syracuse (N.Y.) University on Nov. 3 increased the number of confirmed cases related to an ongoing mumps outbreak among students to 37, marking a 13-case increase since Oct. 13.

Officials also reported 76 probable cases linked to the outbreak, which started in August. In October, the university began offering previously vaccinated students a third dose of the measles, mumps and rubella vaccine to safeguard against potential waning immunity. More than 4,300 Syracuse students received the third MMR dose.

The mumps can cause painful, swollen salivary glands. It is a highly contagious illness transmitted by person-to-person contact and is typically accompanied by initial symptoms such as fever, headache, muscle aches, tiredness and loss of appetite.

Drug-resistant tuberculosis

As of Nov. 6, Minnesota's Ramsey County reported 17 cases of drug-resistant tuberculosis over the last two years, representing the largest such outbreak in the nation.

Of the 17 individuals infected, six died. Three of the deaths were directly attributed to TB. Ten cases were identified among elderly adults who participated in activities at a local senior center. All infected individuals required hospitalization. Fourteen cases occurred among the county's Hmong community.

State health officials suspect the outbreak originated overseas, as some of the infected individuals once resided in a Thai refugee camp where tuberculosis infections were common. The Minnesota Department of Health is working with the Hmong community to raise awareness about TB and monitoring 500 people for possible exposure as of Nov. 6.

TB is caused by Mycobacterium tuberculosis. Infection occurs when someone with active TB transmits the bacteria to another person via coughing, speaking or singing. Treatments for drug-resistant TB can take up to two years.